Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63C—LAUNCHING, HAULING-OUT, OR DRY-DOCKING OF VESSELS; LIFE-SAVING IN WATER; EQUIPMENT FOR DWELLING OR WORKING UNDER WATER; MEANS FOR SALVAGING OR SEARCHING FOR UNDERWATER OBJECTS
  • B63C3/00—Launching or hauling-out by landborne slipways; Slipways
  • B63C3/06—Launching or hauling-out by landborne slipways; Slipways by vertical movement of vessel, i.e. by crane

Definitions

• the present invention relates to a method of distributing the loads generated between a ship and a supporting structure on which the ship is resting.
• the invention has particular efficacy in the field of dry docking marine vessels and is described in detail herein in that context.
• United States patent 4,087,979 also owned by applicant and still in force, discloses and claims improvements to the dry /*ock of 3,073,125, inter alia by way of enabling construction in module form off site, and articulating the structure at positions along its length, so as to reduce the adverse effect of local load concentrations on the ships' hull.
• dry docks There are a total of one hundred and sixty eight such dry docks in operation in sixty two countries. Both types of dry dock are operated by hoist winches which in turn are driven by a.c. synchronous motors, so as to ensure lift synchronism. Control is computerised and includes manual override.
• the apparatus used in practising the method provides hoist load indicating means in the load path of each hoist winch, in a system of hoist winches on opposing quays.
• the load indicating means is of the kind which generates electrical signals when acted on by a said load.
• Means are provided which receive and condition the signals and further means are provided which receive the conditioned signals and use them to react upon the system and thereby control it.
• the further means also uses said signals to generate visual displays of load magnitudes, current magnitudes, weight distributions and total weights, as experienced by the hoist winches.
• Figure 1 is a diagrammatic side elevation of a dry dock incorporating the present invention.
• Figure 2 is a diagrammatic view on line 2-2 of Figure 1.
• Figure 3 is a pictorial view of a hoist winch connected for control by the present invention.
• Figure 4 is a view in the direction of arrow 4 in Figure 1.
• Figure 5 is a schematic diagram of a signal conditioning circuit incorporated in the present invention.
• Figure 6 is a dual graphic and actual numerical value display of a ships weight distribution in a hoist winch system incorporating six pairs of opposed winches of the kind depicted in Figure 3.
• a platform 13 of the kind described in US patent 4,087,979 supports a ship 9 for vertical movement with respect to a quay 10 ( Figure 2) .
• the platform 13 includes main transverse beams 20 the ends of which lie within cutouts 17 in the opposing faces of the quays 10 ( Figure 1) and 12 ( Figure 4) .
• a hoist winch 19 one of a series of opposed pairs of hoist winches 19 as seen in Figure 4, is fixed to the quay and supports further sheaves 21 in approximately vertical alignment with the sheaves 18, and further includes a winch drum 29.
• a wire rope 27 is fixed by one end to a load cell 25 which also doubles as a clevis pin, and which is fixed to the end of the structure of the hoist winch 19.
• a signal conditioning circuit 28 is fixed to or near the hoist winch structure 19 and is connected to the load cell clevis pin 25.
• Each winch drum 29 is driven by an a.c. synchronous motor 33 via a step down gear arrangement 35 and a toothed wheel 37 on the end of the drum 29.
• a totally enclosed gearbox could be substituted.
• a limit switch 41 is fastened to the structure of the hoist winch 19 and a contact pad 43 is carried by the beam 20.
• the limit switch is pre ⁇ set and when the platform 13 rises to its desired height during operations, the pad 43 contacts the limit switch 41 which then is actuated to effect halting of the platform 20.
• FIG. 4 During operation of the hoist winches 19 to raise or lower the platform 13 and its associated ship 9, the conditioning circuit 28 receives electrical signals from the load cell 26 associated with that winch 19.
• the circuit 28 which in Figure 4 is depicted by a box, is more explicitly illustrated in Figure 5 to which brief reference is now made.
• a d.c. input 60 is converted at 62 into a sinewave plus and minus d.c. voltage.
• the output from 62 is regulated at 64 and the resulting regulated, d.c. exitation voltage is passed to the load cell 25.
• the output voltage from the load cell 25 is amplified at 66 and then converted at 68 to a current output for use in the computer, to which it is passed via a power handling MOSFET transducer 70.
• the computer 47 sends control signals to the ship lift control panel which can stop or allow operation of the hoist winches 19 and sends further signals to a visual display unit 49 so as to display information which has been derived from the signals concerning the operating performance of the hoist winches 19, i.e. the loads being sensed and the weight of the vessel being supported.
• Figure 6 displays in both histogram and numerical form, the manner in which a particular ship's weight is distributed over the hoist winches 19.
• Opposed winch stations 1A and IB are each experiencing a load of 73.8 tons.
• Stations 4A and 4B are each experiencing c. load of 256 tons * and stations 6A and 6B are each experiencing a load of 72 tons.
• load cell 25 in the form of a clevis pin.
• other forms of load cell may be used, and positioned anywhere in the load path of the loads which the hoist winches 19 experience during operation.
• load cells can be positioned on the support structure 51 of the hoist winch sheaves 21, or at 53 between the hoist winches 19 and the quays 10 and 12, or at the clevis pin supports, i.e., a normal clevis pin 25 is used and supported on a load cell of appropriately adapted shape.
• the dry dock is first submerged and a ship floated over it.
• the hoist motors 19 are then activated in unison to raise the dock and ship to dock level, or at least to a height at which the ship is clear of the water.
• the hoist winches 19 on the heavily loaded side can be lowered until the load is equalised between each opposing pair of hoists.
• the hoist winches 19 on the more lightly loaded side could be raised to give the same result.
• one or more beams may be lowered at that point where the load concentration is highest so that adjacent beams can increase their share of the vessel's load.
• Such a high concentration may for example occur where a portion of the platform, or any padding structure between the ship and the platform on which the hull rests, are set higher than the adjacent structure; or alternatively, a high load concentration may occur where some projection from the ship's hull makes contact with the structure; alternatively, high load concentrations can occur due to a number of other reasons.
• one or more beams is/are lowered until adjacent beams accept a greater ' share of the loading.
• the beams are moved downwards in small increments whilst observing the changes in displayed loads at each hoist, until a more acceptable distribution of the load is achieved.
• This facility also enables the Shipbuilder to induce or relieve stresses and/or strains in the hull as necessary.
• One benefit of this would be to allow the alignment or re-alignment of hatch openings.
• the Shipbuilder is able to adjust the supports adjacent to the stern section of a ship in order that the ship's propulsion shafts may be realigned.
• the facility also allows the Shipbuilder to use the platform as a manipulator when joining portions of a ship's hull which may have been separated in order to perform a lengthening project or in some other form of ship conversion or new ship construction.
• the articulated platform construction also allows the platform structure to be separated so that certain sections may be operated independently. This effectively converts the platform into two or more independent platforms which can be used for handling two or more vessels simultaneously.
• the facility can be used for propulsion shaft removal (where the shaft is withdrawn at a downward angle) or for removing a vessel's rudder. The operator is able to control each of these sections separately whilst observing the variation in loads on the display.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Ship Loading And Unloading (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Refuse Collection And Transfer (AREA)
• Nitrogen Condensed Heterocyclic Rings (AREA)
• Polishing Bodies And Polishing Tools (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Forklifts And Lifting Vehicles (AREA)
• Carriers, Traveling Bodies, And Overhead Traveling Cranes (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

Publications (1)

Family

ID=24880364

Family Applications (1)

Country Status (13)

Cited By (3)

Families Citing this family (11)

Citations (7)

Family Cites Families (15)

• 1991
  • 1991-06-18 US US07/717,011 patent/US5314263A/en not_active Ceased
• 1992
  • 1992-06-12 JP JP50096293A patent/JP3162712B2/ja not_active Expired - Fee Related
  • 1992-06-12 DE DE69205802T patent/DE69205802T2/de not_active Expired - Lifetime
  • 1992-06-12 ES ES92913536T patent/ES2079196T3/es not_active Expired - Lifetime
  • 1992-06-12 AU AU22257/92A patent/AU651489B2/en not_active Expired
  • 1992-06-12 EP EP92913536A patent/EP0542994B1/en not_active Expired - Lifetime
  • 1992-06-12 DK DK92913536.6T patent/DK0542994T3/da active
  • 1992-06-12 AT AT92913536T patent/ATE129681T1/de active
  • 1992-06-12 WO PCT/US1992/004816 patent/WO1992022457A1/en active IP Right Grant
• 1993
  • 1993-01-30 KR KR1019930700268A patent/KR100247824B1/ko not_active IP Right Cessation
  • 1993-02-08 FI FI930533A patent/FI109676B/fi not_active IP Right Cessation
  • 1993-02-09 NO NO930451A patent/NO309136B1/no not_active IP Right Cessation
• 1995
  • 1995-12-19 GR GR950403585T patent/GR3018453T3/el unknown
• 1998
  • 1998-11-24 US US09/198,332 patent/USRE37061E1/en not_active Expired - Lifetime

Patent Citations (7)

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